Scholar Rock will be initiating a Phase II trial of its spinal muscular atrophy pipeline drug apitegromab alongside a GLP-1 receptor agonist (GLP-1ra) in patients with obesity months after being given the green light by the US Food and Drug Administration (FDA).
The company had its investigational new drug (IND) application for the myostatin inhibitor cleared by the FDA for a Phase II proof-of-concept trial of apitegromab to treat obesity in patients taking a GLP-1ra.
Apetigromab acts by blocking the activation of latent myostatin. Myostatin is a member of the TGF beta superfamily of growth factors that is expressed primarily in skeletal muscle cells to inhibit muscle growth.
The Phase II trial, due to begin in mid-2024, will be a randomised, double-blind, placebo-controlled, multi-centre study to evaluate the effect of apitegromab to safely preserve lean muscle mass as an adjunctive therapy in overweight and obese adults that are taking a GLP-1ra. Trial data is expected in mid-2025.
Scholar Rock reported in a company presentation that it has pre-clinical evidence which indicates maintenance or increase in lean muscle mass and enhancement of fat loss when a myostatin selective inhibitor is combined with GLP-1ra.
CEO of Scholar Rock, Dr. Jay Backstrom said: “Maintaining lean mass during weight loss is important to overall metabolic health, and we look forward to initiating the Phase II proof-of-concept trial in apitegromab to validate our differentiated approach of selectively targeting only the pro- and latent forms of myostatin to retain muscle mass.”
Scholar Rock is also developing SRK-439, a novel investigational selective myostatin inhibitor, optimised for the treatment of obesity. The company plans to file an IND for SRK-439 in 2025.
SMA drug being investigated in obesity
Apitegromab is being investigated for the use in spinal muscular atrophy (SMA) with a Phase III trial, the SAPPHIRE trial (NCT05156320), testing it alongside current standard of care.
The FDA granted fast track, orphan drug and rare pediatric disease designations, and the European Medicines Agency (EMA) has granted priority medicines (PRIME) and orphan medicinal product designations, to apitegromab for the treatment of SMA.
Obesity landscape
The approvals of GLP1ra’s Ozempic and Zepbound are revolutionising the obesity market. The candidates are dominating the market but there are other drugs with novel mechanisms of action for obesity in late stage trials.
By 2030, the anti-obesity medicine market could grow to $30bn for the seven major markets (US, France, Germany, Italy, Spain, UK, and Japan), according to GlobalData’s Epidemiology and Market Size database.
GlobalData’s Pharma Intelligence Center’s Sales and Forecast database states that the combined sales of Wegovy, Ozempic, and Mounjaro in 2022 equate to $9.8bn. GlobalData forecasts that obesity drug Mounjaro will surpass Ozempic’s sales, by rising to $27bn in sales by 2029.
GlobalData is the parent company of the Clinical Trials Arena.
